Switching Low Noise Amplifier - Patent 8130033

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Switching Low Noise Amplifier - Patent 8130033 Powered By Docstoc
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Description: BACKGROUND 1. Field of the Invention The embodiments of the invention generally relate to low noise amplifiers for receiver circuits, and, more particularly, to a low noise amplifier capable of accommodating multiple input signals. 2. Description of the Related Art Cellular phone manufactures often need to accommodate several different cellular standards (i.e., several different frequency bands). The different cellular standards are typically within the 800 MHz to 900 MHz range and/or within the 1800 MHzto 1900 MHz range. Broadband wireless devices similarly may operate at several different standards (e.g., several different Worldwide Interoperability for Microwave Access (WiMax) standards). The different WiMax standards are typically within the 2 to11 GHz range and currently the focus is on 2.5 GHz, 3.5 GHz and 5.8 GHz. Systems (e.g., cellular or broadband wireless communication devices, test applications, radiometers, etc.) that accommodate multiple frequencies, antennas and/or calibrated noise sources generally will have a receiver circuit with multiple frontends. Each front end of the receiver circuit incorporates a switch that provides a connection between a specific device antenna or noise source and a corresponding low noise amplifier (LNA). Each low noise amplifier is tuned to a desired frequency fornoise figure and gain in order to amplify weak signals emanating from that antenna or noise source. The frequency can be the same or different for each low noise amplifier. For example, cellular or broadband wireless communication device, having asingle antenna, can incorporate multiple LNAs to allow for operation at multiple different frequencies. Alternatively, a radar application can be connected to multiple antennas via multiple LNAs that operate at the same or different frequencies. Thedifferent front end switches allow the receiver circuit to switch between different LNA inputs. However, a number of problems are associated with incorporating mult